Peat is one of the most distinctive flavours in Scotch whisky. It is commonly responsible for the smoky character found in many beloved malts, particularly those from Islay. But peat is far from a one-dimensional ingredient. Depending on where it comes from, it can contribute flavours ranging from medicinal smoke and seaweed to earthy, herbal and subtly floral notes.
It Starts with the Land
Peat forms over thousands of years as partially decayed vegetation accumulates in waterlogged conditions. The plants that make up the peat vary by location, influenced by local climate, geology and the surrounding environment. When peat is burned to dry malted barley, these differences influence the smoke compounds absorbed by the grain — and ultimately the character of the whisky.
Barry Harrison’s study into the "Composition of Peats Used in the Preparation of Malt for Scotch Whisky Production: Influence of Geographical Source and Extraction Depth" aimed to determine whether peats from different parts of Scotland are chemically distinct and could impart different flavours.
So what?
The analysis found differences in the level of phenols and guaiacol compounds across the regions, something that didn't surprise industry and consumer experts.
- Islay Peat (Maritime & Medicinal): Rich in marine influence, seaweed, and decaying saltwater flora. It produces high levels of bromophenols and phenols, giving whiskies like Laphroaig, Ardbeg, and Lagavulin distinct notes of iodine, brine, tar, and antiseptic.
- Highland and Mainland Peat (Woody & Earthy): Composed more heavily of inland grasses, bracken, and decaying timber. This delivers more guaiacols, resulting in savoury, smoky, and dry, woody profiles.
- Orkney Peat (Floral & Sweet): Influenced by dense coastal heather rather than deep seaweed. It yields compounds like syringols, imparting a distinct floral, sweet-smoke character to expressions like Highland Park.
More Than Just Smoke
Regional peat is only one part of the story. The amount of peat used, where distilleries source all their peat, the way the barley is malted, fermentation, distillation, cask char and maturation all influence the final whisky. Two distilleries using peat from similar surroundings can produce remarkably different spirits.
Ultimately, peat is a reminder of how closely Scotch whisky is connected to its landscape. Every region brings its own ingredients and environment to the process, creating a spectrum of flavours that goes far beyond smoke.
Same ingredient. Different places. A world of flavour.